3,1

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

R. C. Read, Some Enumeration Problems in Graph Theory. Ph.D. Dissertation, Department of Mathematics, Univ. London, 1958.

Sequence in context: A013434 A013436 A013437 this_sequence A015033 A126677 A054328

Adjacent sequences: A006711 A006712 A006713 this_sequence A006715 A006716 A006717

nonn

N. J. A. Sloane (njas(AT)research.att.com).